DVT Apparatuses
Gaymar Industries, Inc. is the assignee of this application and expired U.S. Pat. No. 4,597,384. The '384 patent is incorporated herein by reference as disclosing a well-made deep vein thrombosis cuff. In the '384 patent, Gaymar wrote, “[T]herapeutic and prophylactic devices for the alleviation of deep venous thrombosis by mechanical as opposed to chemical means. Deep venous thrombosis (DVT) is a condition in which clotting of venous blood occurs generally in the lower extremities due to lack of sufficient muscular activity in the lower extremities. Thus it is important that the velocity of blood flow in the patient's extremities be maintained at the requisite level in order to prevent pooling of blood in such extremities so that stasis of blood will not develop. This is particularly important since it is well known that stasis of blood is a significant cause leading to the formation of thrombi in the patient's extremities which could ultimately cause the death of the patient.
Devices are presently in use for the purpose of increasing blood velocity to prevent problems set forth above. Many of these devices comprise compression sleeves which fit over and around the limb requiring care. Fluid pressure producing means are provided for sequentially inflating the compression sleeve and allowing for a simultaneous deflation of all sleeve components.
Applicant's U.S. Pat. No. 4,453,538 which is entitled “Medical Apparatus” and issued on Jun. 12, 1984, is hereby and herewith incorporated for all of its disclosure into this application. Among other features this patent describes a flexible pad formed for external enwrappment about a patient's limb. The pad includes a plurality of relatively large individual fluid receiving cells adapted to receive and retain sufficient fluid to exert pressure upon the enwrapped limb for a specified period of time. More particularly, the cells are sequentially pressurized starting at the limb extremity and proceeding in the direction of the patient's heart. It is desirable that the sleeve compression pressure proceed smoothly and [progressively] along the patient's limb from the extremity heartward. Most pressure sleeves currently in use cannot do this. In fact most of them leave continuous pressure gaps between respective sleeve portions. Such results are undesirable.
In view of the foregoing it is an object of [the '384 patent] to provide a compression sleeve for a patient's limb which will provide a smooth pressure flow with no pressure gaps extending completely around the patient's limb.
It is yet another object of [the '384 patent] to provide a device for use in applying successive compressive pressures against a patient's limb to produce a smooth pumping action from the patient's limb extremity heartward.
It is a still further object of [the '384 patent] to provide a sleeve for use in applying compressive pressures against a patient's limb wherein the sleeve comprises a plurality of laterally extending separate fluid pressure members arranged longitudinally along the sleeve from a lower portion of the encased limb to the upper portion thereof with the adjacent lateral edge portions of adjacent pressure members being curved upwardly and then downwardly in unison whereby the respective contiguous edges thereof follow each other so that when pressure is sequentially applied from the lowermost pressure members upward there will never be a continuous circumferential pressure gap on any lateral circular portion of the encased limb.
Another object of [the '389 patent] is to provide a device of the type described in the proceeding object and further wherein the successive pressurization of each pressure member from the lowermost heartward produces a plurality of circumferential spaced radially inward maximum and minimum forces interdigitated with successive pressure members having similar maximum and minimum forces to produce a smooth gap free pressurization from start to finish.”
Gaymar's apparatus is just one of many types of deep vein thrombosis (DVT) apparatuses. There are numerous designs for such DVT apparatuses. Representative samples of such DVT apparatus designs are found, and hereby incorporated by reference, in the following U.S. Pat. No.: 2,531,074 to Miller, Nov. 21, 1950; U.S. Pat. No. 4,091,804 to Hasty, May 30, 1978; U.S. Pat. No. 4,269,175 to Dillon, May 26, 1981; U.S. Pat. No. 4,343,302 to Dillon, Aug. 10, 1982; U.S. Pat. No. 4,396,010 to Arkans, Aug. 2, 1983; U.S. Pat. No. 4,989,589 to Pekanmaki et al., Feb. 5, 1991; U.S. Pat. No. 4,311,135 to Brueckner et al., Jan. 19, 1982; U.S. Pat. No. 5,080,089 to Mason et al., Jan. 14, 1992; U.S. Pat. No. 5,186,163 to Dye, Feb. 16, 1993; U.S. Pat. No. 5,383,894 to Dye, Jan. 24, 1995; U.S. Pat. No. 5,554,103 to Zheng et al., Sep. 10, 1996; U.S. Pat. No. 5,591,200 to Cone et al., Jan. 7, 1997; U.S. Pat. No. 5,626,556 to Tobler et al., May 6, 1997; U.S. Pat. No. 5,795,312 to Dye, Aug. 18, 1998; U.S. Pat. No. 5,830,164 to Cone et al., Nov. 3, 1998; U.S. Pat. No. 5,876,359 to Bock et al., Mar. 2, 1999; U.S. Pat. No. 5,997,540 to Zheng et al., Dec. 7, 1999; and U.S. Pat. No. 6,176,869 to Mason et al., Jan. 23, 2001.
Some of the above-identified references disclose DVT apparatuses having a therapy pad with at least two chambers and each chamber receives, through a conduit, a fluid from a source (a “fundamental compression therapy pad design”). The fluid can (a) return to the source through a return conduit or the original conduit (“recirculation systems”), (b) be directed toward a receiving unit (not the source) through a return conduit (“receiving system”), or, alternatively, (c) permeate through apertures in the chambers (normally using air as the fluid and commonly referred to as a “low air-loss system”). The alternative method is preferred if the fluid is a gas; and the former methods are desired if the fluid is a liquid (like an aqueous fluid or a non-aqueous fluid) or a gas (like air). In any case, the fluid is pressurized. The fluid pressure in each chamber can be the same or different, depending on the desired result. For example, the fluid in:                (a) chamber 1 is 50 mm Hg, chamber 2 is 50 mm Hg and so on; (Uniform pressure)        (b) chamber 1 is 80 mm Hg, chamber 2 is 40 mm Hg, and chamber 3 is 20 mm Hg; (Sequential downward pressure)        (c) chamber 1 is 60 mm Hg, chamber 2 is 40 mm Hg, chamber 3 is 60 mm Hg, and chamber 4 is 20 mm Hg; (Alternating Uniform/Sequential Downward Pressure)        (d) chamber 1 is 50 mm Hg, chamber 2 is 30 mm Hg, chamber 3 is 50 mm Hg, and chamber 4 is 30 mm Hg; (Alternating distinct uniform pressure) or        (e) combinations thereof.The fluid can also have a desired temperature. As disclosed in U.S. Pat. No. 2,531,074 to Miller at col. 1, lines 50-56; DVT apparatus can control the fluid temperature. The fluid temperature, however in the cited references, is uniform in each chamber of the therapy pad.        
The fluid receiving cells can be made of a single material or a plurality of materials. Whatever number of materials are used, the material that contacts the patient's skin should be of a material or combination of materials that effectively transfers thermal energy to the patient or receives thermal energy from the patient (hereinafter “Transfer Material”). Examples of such transfer materials that have been used in the past include and are not limited to polymeric materials like polyethylene, polymeric materials with metallic materials (like rivets) positioned on and within the polymeric material, metallic-polymeric materials, and metallic materials.
All of the above variations of (a) fluid pressures, (b) recirculation systems, (c) constant fluid temperature in each chamber, (d) air-loss systems, (e) compression DVT systems, and (f) fundamental compression therapy pad designs, revert at least to the late 1970's.
Hypo/Hyperthermia Control Devices
In this application, we need to also discuss hypo/hyperthermia blankets. One type of hyper/hypothermia blankets are forced-air blankets. Those blankets have been litigated for many years. One such case is Augustine Medical, Inc. v. Gaymar Indus., Inc. (the assignee of this application), 181 F. 3d 1291, 50 USPQ2d 1900 (Fed. Cir. 1999). In that case, Judge Radar concluded that Gaymar's forced-air blankets did not infringe any of Augustine's patents at issue, and wrote, “Convective thermal blankets inflate to direct warm (or cool) air onto a person. Surgeons often use these blankets during and after an operation to prevent or treat hypothermia caused by surgical conditions. Hypothermia results when a patient's body temperature drops below a certain threshold. Surgery often presents the threat of hypothermia. A patient's body temperature may drop significantly during surgery because anesthesia prevents the patient's body from regulating its own temperature. Additionally, operating rooms—kept cool to accommodate the surgeon's working conditions and to reduce the spread of germs—can chill patients. Moreover, surgery often calls for administration of cool intravenous fluids at a time when the patient's body cavity is open.
A convective thermal blanket over the patient is thus necessary to prevent or treat hypothermia during and after surgery. Heated air from a warming unit inflates the blanket. Once inflated, the blanket directs heated air onto the patient through small holes (or “exit ports”) in the undersurface of the blanket. With careful use, a convective blanket regulates patient temperature and prevents hypothermia . . . . [Gaymar's blankets] feature an inflatable quilt-like structure [, . . . ] attach two sheets of the same amount of flexible, lightweight material around their periphery and at various spots along their surfaces. In operation, heated air flows onto a patient's body from holes in the undersurface of [Gaymar's blankets], but [Gaymar's blankets] do not form a self-supporting or Quonset hut-like structure. Instead, [Gaymar's blankets] lie flat when inflated on a flat surface and rest substantially on a patient when in use . . . . Gaymar began selling forced-air blankets in March 1992.” And one of those blankets is Gaymar's THERMACARE quilt.
Alternatively, other types of hypo/hyperthermia blankets are sold by Gaymar. An example of these blankets is Gaymar's DHP 600 hyper/hyperthermia blanket. That blanket operates differently from the forced-air blankets. Those blankets overlay a user and receive a fluid having a predetermined temperature. The fluid circulates through a cavity defined in the blanket that is to be positioned on a patient. The fluid (a) transfers its thermal energy to the patient and/or (b) receives the patient's thermal energy to control the patient's body core temperature. A description of those blankets is set forth in U.S. Pat. No. 6,375,673, which is hereby incorporated by reference in this application and which is licensed to the assignee of this application.
These blankets are extremely effective in altering the body core temperature of a patient. A problem with these devices is that some people claim those prior art hypo/hyperthermia blankets are bulky and difficult to use because those blankets cover too much of the patient. To address that problem, applicants have found a solution. The solution is set forth in the present application.
Negative Therapy Devices
Stanford University is the assignee of U.S. Pat. Nos. 5,683,438; 6,602,277; 6,673,099; 6,656,208; 6,966,922; 7,122,047; and 6,974,442. These patents disclose devices that create a negative pressure about a portion of a patient's body having a venous plexus. A venous plexus is a vascular network formed by numerous anastomoses between veins. The venous plexus is normally located at the patient's foot area and hand area. The negative pressure is applied, and simultaneously thermal energy (cold or warm) is applied to the venous plexus area that is subject to negative pressure.
Applying a negative pressure condition to a portion of the body (a) lowers the vasoconstriction temperature and/or (b) increases vasodilation in the body portion that is enclosed. The negative pressure conditions may be provided using any convenient protocol. In many embodiments, the negative pressure conditions are provided by enclosing a patient's venous plexus area in a sealed enclosure, where the pressure is then reduced in the sealed enclosure thereby providing the desired negative pressure. In many of the embodiments, the negative pressure is allowed to leak to the ambient environment through a seal so it does not create a tourniquet effect. A tourniquet effect is undesirable because it terminates the blood flow which is contrary to the intent of Stanford's negative pressure, thermal energy device.
Negative pressure includes conditions where a pressure is lower than ambient pressure under the particular conditions in which the method is applied, e.g., 1 ATM at sea level. The magnitude of the decrease in pressure from the ambient pressure under the negative pressure conditions in one example is at least about 20 mmHg, preferably at least 30 mmHg, and more preferably at least about 35 mmHg, where the magnitude of the decrease may be as great as 85 mmHg or greater, but preferably does not exceed about 60 mmHg, and more preferably does not exceed about 50 mmHg. When the method is performed at or about sea level, the pressure under the negative pressure conditions generally may range from about 740 to 675 mmHg, preferably from about 730 to 700 mmHg and more preferably from about 725 to 710 mmHg.
In practicing the exemplary methods, the negative pressure conditions during contact with the patient's skin may be static/constant or variable. Thus, in certain examples, the negative pressure is maintained at a constant value during contact of the surface with the low temperature medium. In yet other examples, the negative pressure value is varied during contact, e.g., oscillated. Where the negative pressure is varied or oscillated, the magnitude of the pressure change during a given period may be varied and may range from about 85 to 40 mmHg, and preferably from about 40 to 0 mmHg, with the periodicity of the oscillation ranging from about 0.25 sec to 10 min, and preferably from about 1 sec to 10 sec.
The negative pressure is applied to the certain venous plexus area to create vasodilation. That vasodilation results in the thermal energy (1) effectively transferring its thermal energy to the patient to warm the patient's body core temperature, or (2) effectively receiving the patient's thermal energy to cool the patient's body core temperature.
Stanford University disclosed that the thermal energy can be provided from outside the enclosure—for example a heat lamp—if the enclosure allows such thermal energy to penetrate through it or within the enclosure. Within the enclosure, the thermal energy can be provided by an electric thermal blanket or pad; or a conductive conduit or pad that allows a fluid having a desired temperature to flow through it. In both internal thermal energy providing embodiments and variations thereof, the patient's venous plexus is applied to the thermal energy providing device to transfer thermal energy to the patient and/or receive thermal energy from the patient.
“Third Space” in the Human Body
Current scientific literature reveals that inflammatory mediators initiate a biochemical chain of events that increase capillary permeability. These mediators include pharmacologically active amines such as histamine and 5-hydroxytryptamine, polypeptides such as bradykinin, kallikrein and leukotoxine, the prostaglandins, and various complements including derivatives thereof. These mediators act specifically on the junction of the endothelial cells of capillaries so that the junctions cannot contain colloids such as serum albumin within the vessel. The serum albumin escapes into the interstitium creating a nonfunctional “third space”, the volume of which increases proportionally to albumin leakage and the presence of cytokines as well as proteolytic enzyme activities within the matrix. This leakage further widens capillary membrane-mitochondrial distances creating problems of poor diffusion and transport between the circulatory system and the functional cells resulting in cellular anoxia, a cellular energy deficit, and acidosis, and possibly leading to sequential organ failure.
In the past, the problem of the creation of the third space has been approached through pharmacological means. The present invention approaches the problem by controlling the patient's temperature, applying compression therapy to the patient and/or applying pressure therapy to the patient.